Working basic circular buffer with associated unit tests.

.gitignore

@@ -1,5 +1,6 @@
 # executable
-run
+CircularBuffer
+CircularBuffer_test
 
 # gcov files
 *.gcov

Makefile

@@ -6,7 +6,7 @@ BUILD_PATH = build
 BIN_PATH = $(BUILD_PATH)/bin
 
 # executable #
-BIN_NAME = CppQuickStart
+BIN_NAME = CircularBuffer
 
 # extensions #
 SRC_EXT = cpp

README.md

@@ -1,3 +1,3 @@
-CppQuickStart
-=============
-"Empty" project for a quicker start writing something in c++.
+Circular Buffer
+===============
+Efficient custom all-template fixed-size circular buffer in C++.

include/CircularBuffer.hpp

@@ -0,0 +1,98 @@
+#ifndef DEF_CircularBuffer
+#define DEF_CircularBuffer
+
+template<size_t N, typename T>
+class CircularBuffer
+{
+    public:
+        /// Creates a circular buffer of size N containing items of type T, with values uninitialized.
+        CircularBuffer()
+        : data(NULL),
+          readPointer(0),
+          writePointer(0)
+        { data = new T[N]; }
+
+        /// Creates a circular buffer of size N containing items of type T, initialized with the value initValue.
+        CircularBuffer(T const& initValue)
+        {
+            data = new T[N];
+            Fill(initValue);
+        }
+
+        /// Destroys the circular buffer.
+        ~CircularBuffer() { delete[] data; }
+
+        void Fill(T const& initValue)
+        {
+            for(size_t i = 0 ; i < N ; i++)
+                data[i] = initValue;
+        }
+
+        /// Sets the read pointer's absolute position.
+        void SetReadPointer(int i) { readPointer = BoundIndex(i); }
+
+        /// Gets the read pointer's absolute position.
+        int GetReadPointer() const { return readPointer; }
+
+        /// Sets the write pointer's absolute position.
+        void SetWritePointer(int i) { writePointer = BoundIndex(i); }
+
+        /// Gets the write pointer's absolute position.
+        int GetWritePointer() const { return writePointer; }
+
+        /// Returns a reference to the element i in the buffer. The given index is absolute.
+        T & operator[](int i) { return data[i]; }
+
+        /// Returns a constant reference to the element i in the buffer. The given index is absolute.
+        T const& operator[](int i) const { return data[i]; }
+
+        /// Returns a reference to the element i in the buffer. The given index is relative to the read pointer.
+        T & operator()(int i) { return data[(readPointer + i) % (int)N]; }
+
+        /// Returns a constant reference to the element i in the buffer. The given index is relative to the read pointer.
+        T const& operator()(int i) const { return data[(readPointer + i) % (int)N]; }
+
+        /// Writes the value at the current write pointer's location and moves it forward by 1. If the write pointer catches back with the read pointer, false is returned.
+        bool WriteFwd(T const& v)
+        {
+            data[writePointer] = v;
+            writePointer = BoundIndex(writePointer + 1);
+            return writePointer != readPointer;
+        }
+
+        /// Writes the value at the current write pointer's location and moves it backwards by 1. If the write pointer catches back with the read pointer, false is returned.
+        bool WriteBck(T const& v)
+        {
+            data[writePointer] = v;
+            writePointer = BoundIndex(writePointer - 1);
+            return writePointer != readPointer;
+        }
+
+        /// Reads the value at the current read pointer's location and moves it forward by 1. If the read pointer is co-located with the the write pointer at the time of the read, false is returned.
+        bool ReadFwd(T & v)
+        {
+            v = data[readPointer];
+            int readPointerWhenRead = readPointer;
+            readPointer = BoundIndex(readPointer + 1);
+            return writePointer != readPointerWhenRead;
+        }
+
+        /// Reads the value at the current read pointer's location and moves it backwards by 1. If the read pointer is co-located with the the write pointer at the time of the read, false is returned.
+        bool ReadBck(T & v)
+        {
+            v = data[readPointer];
+            int readPointerWhenRead = readPointer;
+            readPointer = BoundIndex(readPointer - 1);
+            return writePointer != readPointerWhenRead;
+        }
+
+        /// Bounds the index between 0 and N;
+        static inline int BoundIndex(int i) { return (i >= 0) ? i % (int)N : ((int)N + (i % (int)N)) % (int)N; }
+
+    protected:
+        T *data;
+        int readPointer;     //!< Read pointer location
+        int writePointer;     //!< Write pointer location
+};
+
+#endif

include/TestClass.hpp

@@ -1,6 +0,0 @@
-#ifndef DEF_TestClass
-#define DEF_TestClass
-
-
-
-#endif

src/TestClass.cpp

@@ -1 +0,0 @@
-#include "TestClass.hpp"

src/main.cpp

@@ -1,7 +1,7 @@
 #include <iostream>
 
 #include <utils.hpp>
-#include <TestClass.hpp>
+#include <CircularBuffer.hpp>
 
 using std::cout;
 using std::endl;

test/Makefile

@@ -6,7 +6,7 @@ BUILD_PATH = build
 BIN_PATH = $(BUILD_PATH)/bin
 
 # executable #
-BIN_NAME = CppQuickStart_test
+BIN_NAME = CircularBuffer_test
 
 # extensions #
 SRC_EXT = cpp

test/src/1_test.cpp

@@ -3,32 +3,214 @@
 
 #include <utils.hpp>
 #include <utils_test.hpp>
+#include <CircularBuffer.hpp>
 
 #define print(x) PRINT_VAR(x);
 #define printvec(x) PRINT_VEC(x);
 #define printstr(x) PRINT_STR(x);
 
-TEST_CASE( "Test case 1", "[test1]" )
+TEST_CASE( "Circular Buffer test 1", "[CircularBufferTest1]" )
 {
     std::cout.precision(16);
 
-    SECTION( "Check almost equal" ) {
-        CHECK(check_almost_equal(1.00, 1.01, 0.1));
-        CHECK(check_almost_equal(1.00, 3.01, 0.01));
-        CHECK(check_almost_equal(1.00, 1.01, 0.001));
-        REQUIRE(true);
+    SECTION( "Check BoundIndex" ) {
+        constexpr unsigned int N = 5;
+
+        for(int i = 0 ; i < (int)(2*N) ; i++)
+            CHECK(CircularBuffer<N,int>::BoundIndex(i) == (i % N));
+
+        CHECK(CircularBuffer<N,int>::BoundIndex(0) == 0);
+        CHECK(CircularBuffer<N,int>::BoundIndex(-1) == 4);
+        CHECK(CircularBuffer<N,int>::BoundIndex(-2) == 3);
+        CHECK(CircularBuffer<N,int>::BoundIndex(-3) == 2);
+        CHECK(CircularBuffer<N,int>::BoundIndex(-4) == 1);
+        CHECK(CircularBuffer<N,int>::BoundIndex(-5) == 0);
     }
 
-    SECTION( "Check almost equal on vectors" ) {
-        unsigned int N = 5;
-        std::vector<double> v1(N), v2(N);
-        for (size_t i = 0; i < N; i++) {
-            v1[i] = double(i);
-            v2[i] = v1[i] + 0.0001;
-        }
+    SECTION( "Check constructors" ) {
+        constexpr unsigned int N = 5;
+        CircularBuffer<N,int> buf(0);
 
-        CHECK(check_almost_equalV(v1, v2, 0.001));
-        CHECK(check_almost_equalV(v1, v2, 0.0001));
-        CHECK(check_almost_equalV(v1, v2, 0.00001));
+        for(size_t i = 0 ; i < N ; i++)
+            CHECK(buf[i] == 0);
+    }
+
+    SECTION( "Check operator[]" ) {
+        constexpr unsigned int N = 5;
+        CircularBuffer<N,int> buf;
+
+        for(size_t i = 0 ; i < N ; i++)
+            buf[i] = i;
+
+        for(size_t i = 0 ; i < N ; i++)
+            CHECK(buf[i] == i);
+    }
+
+    SECTION( "Check operator()" ) {
+        constexpr unsigned int N = 5;
+        CircularBuffer<N,int> buf;
+
+        for(size_t i = 0 ; i < N ; i++)
+            buf[i] = i;
+
+        buf.SetReadPointer(2);
+
+        for(size_t i = 0 ; i < N ; i++)
+            CHECK(buf(i) == buf[(buf.GetReadPointer() + i) % (int)N]);
+    }
+
+    SECTION( "Check ReadFwd() and ReadBck() nominal" ) {
+        constexpr unsigned int N = 5;
+        CircularBuffer<N,int> buf;
+        int v;
+
+        for(size_t i = 0 ; i < N ; i++)
+            buf[i] = i;
+
+        buf.SetWritePointer(1);
+        buf.SetReadPointer(2);
+
+        // read forwards
+        CHECK(buf.ReadFwd(v) == true);
+        CHECK(v == 2);
+        CHECK(buf.GetReadPointer() == 3);
+
+        // read backwards
+        CHECK(buf.ReadBck(v) == true);
+        CHECK(v == 3);
+        CHECK(buf.GetReadPointer() == 2);
+    }
+
+    SECTION( "Check ReadFwd() and ReadBck() error" ) {
+        constexpr unsigned int N = 5;
+        CircularBuffer<N,int> buf;
+        int v;
+
+        for(size_t i = 0 ; i < N ; i++)
+            buf[i] = i;
+
+        buf.SetWritePointer(2);
+        buf.SetReadPointer(2);
+
+        // read forwards
+        CHECK(buf.ReadFwd(v) == false);
+        CHECK(v == 2);
+        CHECK(buf.GetReadPointer() == 3);
+
+        // read backwards
+        buf.SetWritePointer(3);
+        CHECK(buf.ReadBck(v) == false);
+        CHECK(v == 3);
+        CHECK(buf.GetReadPointer() == 2);
+    }
+
+    SECTION( "Check ReadFwd() and ReadBck() wrap-around" ) {
+        constexpr unsigned int N = 5;
+        CircularBuffer<N,int> buf;
+        int v;
+
+        for(size_t i = 0 ; i < N ; i++)
+            buf[i] = i;
+
+        buf.SetWritePointer(0);
+        buf.SetReadPointer(4);
+
+        // read forwards
+        CHECK(buf.ReadFwd(v) == true);
+        CHECK(v == 4);
+        CHECK(buf.GetReadPointer() == 0);
+
+        // read backwards
+        buf.SetWritePointer(3);
+        CHECK(buf.ReadBck(v) == true);
+        CHECK(v == 0);
+        CHECK(buf.GetReadPointer() == 4);
+    }
+
+    SECTION( "Check WriteFwd() and WriteBck() nominal" ) {
+        constexpr unsigned int N = 5;
+        CircularBuffer<N,int> buf;
+
+        for(size_t i = 0 ; i < N ; i++)
+            buf[i] = i;
+
+        buf.SetWritePointer(2);
+        buf.SetReadPointer(0);
+
+        // write forwards
+        CHECK(buf.WriteFwd(10) == true);
+        CHECK(buf.GetWritePointer() == 3);
+        CHECK(buf[2] == 10);
+
+        // write backwards
+        CHECK(buf.WriteBck(15) == true);
+        CHECK(buf[3] == 15);
+        CHECK(buf.GetWritePointer() == 2);
+    }
+
+    SECTION( "Check WriteFwd() and WriteBck() end-of-buffer" ) {
+        constexpr unsigned int N = 5;
+        CircularBuffer<N,int> buf;
+
+        for(size_t i = 0 ; i < N ; i++)
+            buf[i] = i;
+
+        buf.SetWritePointer(2);
+        buf.SetReadPointer(3);
+
+        // write forwards
+        CHECK(buf.WriteFwd(10) == false);       // write pointer reaches read pointer after write
+        CHECK(buf.GetWritePointer() == 3);
+        CHECK(buf[2] == 10);
+
+        // write backwards
+        buf.SetReadPointer(2);
+        CHECK(buf.WriteBck(15) == false);        // write pointer reaches read pointer after write
+        CHECK(buf[3] == 15);
+        CHECK(buf.GetWritePointer() == 2);
+    }
+}
+
+TEST_CASE( "Circular Buffer practical test", "[CircularBufferTestPractical]" )
+{
+    std::cout.precision(16);
+
+    SECTION( "Moving average" ) {
+        constexpr size_t Npts = 10;
+        std::vector<int> x(Npts);
+        for(size_t i = 0 ; i < Npts ; i++)
+            x[i] = rand() % 100;
+
+        PRINT_VEC(x);
+
+        // Compute moving average with absolute coordinates
+        constexpr size_t N = 3;
+        std::vector<int> xAvg(Npts-N);
+
+        for(size_t i = 0 ; i < Npts-N ; i++)
+            xAvg[i] = (x[i] + x[i+1] + x[i+2]) / 3;
+
+        PRINT_VEC(xAvg);
+
+        // Compute moving average with circular buffer
+        std::vector<int> xAvgBuf(Npts-N);
+        CircularBuffer<N,int> buf;
+
+        // Initialise the buffer
+        buf[0] = x[0];
+        buf[1] = x[1];
+
+        buf.SetWritePointer(2);
+
+        for(size_t i = 0 ; i < Npts-N ; i++)
+        {
+            buf.WriteFwd(x[i+2]);
+            xAvgBuf[i] = (buf[0] + buf[1] + buf[2]) / 3;
+        }
+
+        PRINT_VEC(xAvgBuf);
+
+        for(size_t i = 0 ; i < Npts-N ; i++)
+            CHECK(xAvg[i] == xAvgBuf[i]);
     }
 }